Climate and monthly weather forecast
Saint Johns, IL

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Weather in January

January, the same as December, is a wintry winter month in Saint Johns, Illinois, with an average temperature ranging between max 38.8°F (3.8°C) and min 25.7°F (-3.5°C). January is the month that records the lowest temperatures, with averages ranging from a high of 38.8°F (3.8°C) to a low of 25.7°F (-3.5°C). Weather in January »

Weather in February

The last month of the winter, February, is a chilly month in Saint Johns, Illinois, with an average temperature ranging between min 29.5°F (-1.4°C) and max 43.7°F (6.5°C). The introduction of February notes a subtle temperature variation to a chilly 43.7°F (6.5°C) from January's 38.8°F (3.8°C). Weather in February »

Weather in March

The first month of the spring, March, is a cool month in Saint Johns, Illinois, with temperature in the range of an average high of 55°F (12.8°C) and an average low of 38.7°F (3.7°C). With the onset of March, Saint Johns's average high-temperature sees a rise, moving from February's frosty 43.7°F (6.5°C) to a fresh 55°F (12.8°C). Weather in March »

Weather in April

April in Saint Johns, Illinois, is a comfortable spring month, with an average temperature varying between 48.4°F (9.1°C) and 66°F (18.9°C). April's onset brings a rise in the average high-temperature, moving from a fresh 55°F (12.8°C) in March to a comfortable 66°F (18.9°C). Weather in April »

Weather in May

The last month of the spring, May, is a moderately hot month in Saint Johns, Illinois, with temperature in the range of an average low of 58.1°F (14.5°C) and an average high of 75.4°F (24.1°C). The average high-temperature increases in May, moving from an enjoyable 66°F (18.9°C) in April to a moderately hot 75.4°F (24.1°C). Weather in May »

Weather in June

The first month of the summer, June, is still a warm month in Saint Johns, Illinois, with an average temperature varying between 84.6°F (29.2°C) and 66.6°F (19.2°C). June comes with an increase, with the average high-temperature moving from 75.4°F (24.1°C) in May to a still warm 84.6°F (29.2°C). Weather in June »

Weather in July

July is a hot summer month in Saint Johns, Illinois, with an average temperature varying between 87.3°F (30.7°C) and 68.7°F (20.4°C). July is the month when Saint Johns sees the highest average temperatures, with a high of 87.3°F (30.7°C) and a low of 68.7°F (20.4°C). July's heat index is evaluated at a torrid 102.2°F (39°C). Weather in July »

Weather in August

The last month of the summer, August, is another warm month in Saint Johns, Illinois, with temperature in the range of an average low of 66°F (18.9°C) and an average high of 85.5°F (29.7°C). The transition from July to August brings an average high-temperature of a warm 85.5°F (29.7°C), barely different from July's 87.3°F (30.7°C). Weather in August »

Weather in September

September, the first month of the autumn in Saint Johns, is still a warm month, with an average temperature fluctuating between 60.1°F (15.6°C) and 79.7°F (26.5°C). September ushers in a minute temperature change, with average high-temperatures reducing from August's warm 85.5°F (29.7°C) to a still moderately hot 79.7°F (26.5°C). Weather in September »

Weather in October

October, like September, in Saint Johns, Illinois, is another comfortable autumn month, with an average temperature ranging between min 49.3°F (9.6°C) and max 67.1°F (19.5°C). October is characterized by a reduction in the average high-temperature, from a moderately hot 79.7°F (26.5°C) in September to an enjoyable 67.1°F (19.5°C). Weather in October »

Weather in November

The last month of the autumn, November, is also a fresh month in Saint Johns, Illinois, with an average temperature varying between 38.3°F (3.5°C) and 53.6°F (12°C). The commencement of November involves a temperature shift, with the average high-temperature dropping from a refreshing 67.1°F (19.5°C) in October to a cool 53.6°F (12°C). Weather in November »

Weather in December

The first month of the winter, December, is also a frosty month in Saint Johns, Illinois, with an average temperature fluctuating between 31.1°F (-0.5°C) and 43.5°F (6.4°C). December implies a gentle temperature shift, with average high-temperatures reducing from November's fresh 53.6°F (12°C) to a frosty 43.5°F (6.4°C). Weather in December »
Updated: Jun 27, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What month is the coldest?

With average high and low temperatures of 38.8°F (3.8°C) and 25.7°F (-3.5°C) respectively, January is Saint Johns's coldest month.

What is the driest month in Saint Johns?

The month with the least rainfall is January, when the rain falls for 8.4 days and typically collects 1.5" (38mm) of precipitation.

How many days does it rain?

Throughout the year, there are 147.6 rainfall days, and 29.17" (741mm) of precipitation is accumulated.

When does it snow?

January through April, November and December are months with snowfall.

How much does it snow?

Throughout the year, there are 18 snowfall days, and 4.53" (115mm) of snow is accumulated.

What is the month with the least sunshine?

January has the least sunshine of the year, with an average of 4.6h of sunshine.

When is the lowest UV index?

The months with the lowest UV index in Saint Johns are January, February, November and December, with an average maximum UV index of 2.

What is the snowiest month?

The month with the most snowfall is February, when snow falls for 5.1 days and typically aggregates up to 1.5" (38mm) of snow.

When is Daylight Saving Time (DST)?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from CST to CDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from CDT to CST.

What is the rainiest month?

The month with the most rainfall is April, when the rain falls for 15.1 days and typically aggregates up to 3.58" (91mm) of precipitation.

What is the most humid month?

May is the most humid month, with an average relative humidity of 79%.

When it does not snow?

In Saint Johns, snow does not fall in May through October.

When are the longest days?

June has the longest days of the year, with an average of 14h and 48min of daylight.

What is the month with the highest UV index?

June through August, with an average maximum UV index of 6, are months with the highest UV index.

What time of the year is the hottest?

Saint Johns's July weather, with an average high temperature of 87.3°F (30.7°C) and an average low temperature of 68.7°F (20.4°C), tends to be the warmest of the year.

What month has the most sunshine?

July has the most sunshine of the year, with an average of 10.5h of sunshine.

What is the least humid month?

October is the least humid month, with an average relative humidity of 71%.

What is the month with the shortest days?

December has the shortest days of the year, with an average of 9h and 36min of daylight.

Average temperature
Saint Johns, IL

Average temperature - Saint Johns, IL

The warmest month (with the highest average high temperature) is July (87.3°F).
The month with the lowest average high temperature is January (38.8°F).

The month with the highest average low temperature is July (68.7°F).
The coldest month (with the lowest average low temperature) is January (25.7°F).

Average pressure
Saint Johns, IL

Average pressure - Saint Johns, IL

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed
Saint Johns, IL

Average wind speed - Saint Johns, IL

The windiest months (with the highest average wind speed) are January and February (9.6mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).

Average humidity
Saint Johns, IL

Average humidity - Saint Johns, IL

The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).

Average rainfall
Saint Johns, IL

Average rainfall - Saint Johns, IL

The wettest month (with the highest rainfall) is April (3.58").
The driest month (with the least rainfall) is January (1.5").

Average rainfall days
Saint Johns, IL

Average rainfall days - Saint Johns, IL

The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is December (8.2 days).

Average snowfall
Saint Johns, IL

Average snowfall - Saint Johns, IL

The month with the highest snowfall is February (1.5").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days
Saint Johns, IL

Average snowfall days - Saint Johns, IL

The month with the highest number of snowfall days is January (5.4 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

Average daylight / Average sunshine
Saint Johns, IL

Average daylight / Average sunshine - Saint Johns, IL

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).

The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).

Average sunshine days
Saint Johns, IL

Average sunshine days - Saint Johns, IL

The months with the most sunshine days are October and November (19.5 days).
The month with the least sunshine days is May (11.4 days).

Average UV index
Saint Johns, IL

Average UV index - Saint Johns, IL

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average visibility
Saint Johns, IL

Average visibility - Saint Johns, IL

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

Saint Johns, Illinois, USA

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